Pressure control devices for pneumatic circuits

ABSTRACT

Pressure-reducing devices for use in pneumatic systems which include apparatus, such as air cylinders and the like, that are operated from a source of air under pressure. The devices are adjustable so that a common source of high-pressure air can be used in connection with different apparatus operable at different reduced pressures, and the devices will permit optimum selection of air pressures for each such apparatus. In one form, the device is a platelike structure that can be sandwiched in between a conventional solenoid operated air valve and a subplate manifold therefor. Other forms of devices are disclosed for use in other locations in pneumatic systems.

United States Patent Moore 51 Feb. 22, 1972 PNEUMATIC CIRCUITS PRESSURE CONTROL DEVICES FOR 3,199,533 8/1965 Fountain-Barber ..l37/543.l3 3,425,444 2/1969 Jones ..l37/540 [72] Inventor: William Moore, 560 S. Ann Arbor St., primary Klinksiek Sallnfi, Mlch- 48176 Att0rney-Olsen and Stephenson F' [22] iled Mar 16, 1970 ABSTRACT [21] Appl' 19899 Pressure-reducing devices for use in pneumatic systems which 1 include apparatus, such as air cylinders and the like, that are [52] U.S. Cl. "137/ 117 operated from a source of air under pressure. The devices are [5i] Int. Cl ..Fl6k 17/18 adjustable so h a mm n ur e f high-pressure air can [58] Field of Sear h 137/4931, 540, 54313, 493 be used in connection with different apparatus operable at different reduced pressures, and the devices will permit optimum 1 56] defences m selection of air pressures for each such apparatus. In one form, the device is a platelike structure that can be sandwiched in UNITED STATES PATENTS between a conventional solenoid operated air valve and a subplate manifold therefor. Other forms of devices are disclosed 3,l89,046 6/ l 965 Callahan et al. ..l37/540 X for use in other locations in pneumatic systems 3,272,218 9/1966 Johnson ..l37/54O X 1,583,834 5/1926 Humphrey ..l37/493.7 11 Claims, 7 Drawing Figures 4 46 /7 m4 /l V77vya /62 M /7fi l l l M6 m /72 I I l M 7 W w /54 W PAIENT0FEB22 I972 3. 643,684

sum 1 UF 3 INVENTOR 5 76.3 WILLIAM L. MOORE ATTOR NEYS PATENTEDFEBBZ m2 3.643.684

' FIG. 5 I

WNVENTOR WILLIAM L. MOORE BY WM ATTOR NEYS PAIENTEDFEB22 1912 SHEET 3 OF 3 v Wm Wk k y M MY 4 V L mm m M a f INVEN'TOR WILLIAM L MOORE (Zwfl ATTORNEYS l PRESSURE CONTROL DEVICES FOR PNEUMATIC CIRCUITS BACKGROUND OF THE INVENTION The present invention relates to pressure reducers adapted to be mounted in a pneumatic system for making more effective use of high-pressure air.

It is common practice when utilizing pneumatic systems to operate machine tools and the like, to provide air to such machine tools uniformly at a regulated high pressure. This arrangement frequently is unsatisfactory, because it results in a waste of pressurized air in many instances, and it may be harmful to those machine tools that use air at greater pressures than are necessary, Also, it results in maintenance costs of such machine tools which are excessive.

SUMMARY OF THE INVENTION The present invention has overcome the shortcomings of the prior art and has provided pressure-reducing devices which can readily be inserted in a pneumatic system to provide an arrangement for supplying only the needed pressure for the operation of the machine tools, such as air cylinders and the like. This arrangement results in less wear on the cylinder components, and substantially reduces the amount of compressed air needed for the overall operation.

According to one form of the present invention,"a pressure reducer is provided for insertion into a pneumatic system between a source of high pressure air and apparatus, such as air cylinders, which are adapted for using air under pressure. The pressure reducer comprises a body member defining an air supply passageway having a highpressure end for receiving air from the source and a low-pressure end for discharging air at a'lower pressure to the apparatus. A pressureadjusting assembly is mounted in the body member in association with the supply passageway for selectively reducing to a desired magnitude the pressure of the air passing therethrough.

In a preferred form of the invention, the pressure reducer comprises a platelike structure or body member defining the supply passageway, the ends of which are in the upper and -lower surfaces of the structure. The platelike structure is readily adapted to be mounted between the base of a solenoid operated air valve which has a subplate manifold normally mounted on its undersurface. The platelike structure can be sandwiched in between the air valve and its subplate with the ends of the supply passageways in registry with corresponding openings in the air valve and its subplate. This form of the invention is readily adapted for use with air valves of the directional type wherein two or more pressure reducers can be formed in a single platelike structure. In an arrangement such as this, it is desirable that exhausting from the air cylinders occurs through the air valve, and the pressure reducer can readily accommodate this type of operation, because it also contains an exhaust passageway which bypasses the pressure-adjusting assembly and is in communication with the opposite ends of the supply passageway. The exhaust passageway normally will include a check valve or mechanism to prevent flow of pressurized air therethrough during the supply cycle time, but which will permit exhausting of the air through the pressure reducer, during the appropriate time of the machineoperating cycle.

Other forms of the invention may utilize a pressure reducer wherein only a supply passageway is provided, and in still other forms of the invention, the pressure reducer can be employed in conjunction with a flow control assembly which forms a part of the exhaust passageway for the purpose of regulating the rate of exhaust of the air from an air cylinder, thereby controlling the rate of travel of the piston.

Accordingly, it is among the objects of the present invention to provide pressure reducers in different forms for use in pneumatic systems whereby the most effective use of the highpressure air will be realized so as to effect savings of the air, and also so as to minimize the upkeep problems of the machinery.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of one embodiment of the invention sandwiched in between a conventional solenoidoperated directional air valve and its subplate manifold;

FIG. 2 is a top plan view of the embodiment shown in FIG. 1, taken on the line 2-2 of FIG. 1;

FIG. 3 is a bottom plan view of the embodiment, taken on the line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary section taken on the lines 4-4 of FIG. 2;

FIG. 5 is a schematic illustration of a pneumatic system having three branches, and illustrating the embodiment of FIG. I in one of the branches, and illustrating two other embodiments of the invention in the other two branches of the DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring now to the drawings, the invention will be described in greater detail. Attention is directed first to FIG. 5 wherein a pneumatic system 10 is illustrated having an air supply line 12 for receiving air under pressure from a suitable source, not shown. A conventional air filter 14 is in series with a conventional pressure regulator 16 and a conventional lubricator 18. A first branch 20 is provided for supplying air to a first air cylinder 22, a second branch 24 is provided for supplying air to a second air cylinder 26, and a third branch 28 is provided for supplying air to a third air cylinder 30.

The first branch 20 contains a pressure reducer 32, of the type illustrated in FIG. 7, a solenoid-operated directional air valve 34, two conduits 36 and 38 extending between the air valve 34 to opposite ends of the air cylinder 22, each conduit 36, 38 containing therein a conventional flow control device 40, 42, respectively.

The second branch 24 includes a conventional solenoid operated directional air valve 44 and two conduits 46 and 48 extending between the air valve 44 and opposite ends of the air cylinder 26, each conduit 46, 48 including a pressure reducer 50, of the type illustrated in FIG. 6.

The third branch 28 includes the solenoid operated directional air valve 52 assembled together with the pressure reducer 54, of the type illustrated in FIGS. 1-4, and conduits 56 and 58 which extend from the assembly of the air valve 52 and pressure reducer 54 to opposite ends of the air cylinder 30. The operation of the pneumatic system with its three branches 20, 24 and 28 will be described after the individual pressure reducers 32, 50, 54 have been explained in greater detail.

Attention is directed first to the pressure reducer 32 illustrated in FIG. 7. As there shown, the pressure reducer 32 has a body member 60 defining a passageway therethrough identified by the number 62. The latter has a high pressure end 64 for receiving air from the source, and a low pressure end 66 nun mm for discharging air at a relatively lower pressure to the air cylinder 22. A wall 68 extends across the passageway 62 and defines a port 70 which is a part of the passageway 62 to provide communication between the high and low pressure ends 64 and 66. A pressure adjusting or reducing check valve assembly 72 is mounted in the body member 60 in operative association wit the port 70. The assembly 72 includes a check valve element 74 having a seal 76 on its end face for abutment with the wall 68 around the periphery of the port 70. The check valve element 74 is arranged to seat on the downstream side or low pressure side of the wall 68 and preferably is piston shaped so as to provide a relatively long skirt 78 into which a calibrated compression spring 80 is inserted. An adjustment cap 82 is threadedly connected to the body member 60, and its position is precisely located by means of a spacer element 84. The adjustment member 82 has a shirt 86 into which the skirt 78 is telescoped and by virtue of this arrangement the compression spring 80 is held in a state of compression between the body member 60 and the valve element 74 so that the latter is urged against the ported wall 68 by a pressure of a fixed magnitude. It will be recognized that the extent of the compression forces exerted by the valve element 74 can be varied merely by adjusting the cap 82 axially relative to the body member 60. If it is desired that the adjustment be retained at a fixed location, this can be accomplished by inserting a spacer member 84 of a desired thickness. Conventional O-ring 88 is provided between the cap 82 and the body member 60 so as to provide an effective seal.

In operation, the pressure reducer 32 will function to maintain the port 70, and thereby the passageway 62, closed to air under pressure supplied to the high-pressure end 64 until such pressure exceeds a preselected magnitude established by the calibrated spring 80. When such pressure exceeds the preestablished magnitude, the valve element 74 will be lifted from its seat permitting air to flow through the port 70 and out of the low-pressure end 66. The pressure of the air being discharged from the low-pressure end 66 will then be a direct function of the difference between the air pressure at the highpressure end 64 and the opposing pressure exerted by the pressure reducer 72. Thus, if air pressure in the system is discharged from the pressure regulator 16 at 80 pounds per square inch, and it is desired to utilize air at 60 pounds per square inch in the first branch 20, this can readily be accomplished by inserting a pressure reducer 32 into the circuit in the position indicated in FIG. 5. The pressure reducer 32 will be set so that the pressure adjusting assembly 72 releases air from the low-pressure end 66 at 60 pounds per square inch. By virtue of this arrangement, air at 60 pounds per square inch will flow to the air valve 34 for selective discharge to the conduits 36 and 38. Air will then flow to the selected end of the cylinder 28 via one of the flow control units 40 or 42 at the pressure of 60 pounds per square inch, and the other of the flow control units 40 or 42, which is in communication with the exhaust end of the cylinder 22 will then regulate the rate of discharge of air from the cylinder 22, thereby controlling the rate of travel of the piston, in the conventional manner.

Attention is next directed to the embodiment of the invention illustrated in FIG. 6 and shown in the second branch 24 of the schematic diagram of FIG. 5. The pressure reducer 50 includes a body member 90 which defines a supply passageway 92 having a high-pressure end 94 and a low-pressure end 96. A wall 98 extends across the passageway 92 and has a port 100 which is a part of the passageway 92. A pressure adjusting or reducing check valve assembly 102 is mounted in the body member 90 in operative association with the port 100 for normally closing the same. The pressure reducing assembly 102 can, if desired, be constructed and arranged identically the same as the pressure-reducing assembly 72 illustrated in FIG. 7. The pressure'reducing assembly 102 differs from the assembly 72 in that the cap 104 is threadedly connected to the body member 90 in a fixed position, and for adjustment purposes an adjustment screw 106 has been provided which is threadedly connected to the cap 104 and has a skirt 106 into which the end of the compression spring 108 is retained. Thus, the spacer element 84 has been eliminated, and for adjustment purposes, the adjustment screw 106 has been provided. The latter can be advanced into or withdrawn a limited extent from its shown position to vary the compression forces exerted by the compression spring 108 on the valve element 110. in other respects the two pressure-reducing assemblies 102 and 72 are the same, and both serve to reduce the air pressure supplied through the inlet end 94 to the outlet end 96.

The pressure reducer 50 also includes in its body member an exhaust passageway 112 which is in communication with the opposite ends 94 and 96 of the supply passageway 92 so as to bypass the port and the associated pressurereducing assembly 102. The exhaust passageway 112 contains a flow control assembly 1 14 which normally closes the exhaust passageway and opens only when the pressure on the lowpressure end 96 exceeds the pressure at the high pressure end 94 of the supply passageway 92. By virtue of this arrangement, air can be exhausted from the cylinder 26 through one or the other of the pressure reducers 50.

The flow control assembly 1l4includes a check valve element 116 having a seal 1 18 on its end face for seating against the shoulder 120 in the passageway 112. The valve element 116 is free floating in the skirt 120 of the cap 122 and has adjacent to its end face a flexible disk 124 retained in place by a snap ring 126. By virtue of this arrangement, so long as the air pressure at the end 94 is greater than the air pressure at the end 96, the element 116 will be urged into a closed position, such as is shown in FIG. 6, and under circumstances wherein the exhaust pressure at 96 exceeds that at the end 94, the element 116 will be urged to the right and exhaust air can bleed around the periphery of the flexible disk 124. The extent to which the element 116 can move to an open position can be regulated by the stop pin 128 which is threadedly connected at its one end to the cap 122. Thus, in the second branch of the circuit illustrated in H6. 5, the pressure reducers 50 will function to permit air at any selected pressure equal to or less than that from the source to be delivered to the working end of the piston 26, and the exhaust air from the other end can pass through the other pressure reducer to be discharged to exhaust via the directional air valve 44.

Referring next to FIGS. l-5, the pressure reducer 54 will be described. As there shown, the pressure reducer 54 is sandwiched in between the'directional air valve 52 and the subplate manifold 130 which normally is mounted directly on the underside of the air valve 52. The subplate manifold 130 is a conventional construction having inlet ports 132 and 134 to which the conduits 56 and 58 are connected. A similar port, not shown, normally will be located on the opposite side of the subplate manifold 130. to which the high-pressure air from conduit 28 is connected. Exhaust connections can be provided at either 136 or 138 which correspond to the outlet indicated at 140 in Fig. 5. The directional air valve 52, pressure reducer 54, and subplate manifold 130 are secured together by a plurality of screws 142.

The pressure reducer 54 includes a body member or platelike structure 144, which for ease of manufacture may be made from a plurality of segments, in which the plurality of passageways and ports can more readily be constructed. The platelike structure 144 defines a supply passageway 146 the high pressure end of which is in the upper surface of platelike structure 144, and the low-pressure end of which is in the lower surface of platelike structure 144. The ends 148 and 150 are located so that they will be in registry with the corresponding passageways 152 of the air valve 52 and 154 of the subplate manifold 130.

The supply passageway 146 has a transverse wall 156 in which is located a port 158 which fonns a part of the passageway 148 and provides communication between the high and low pressure ends 148 and 150. A pressure adjusting or reducing check valve assembly 160 is mounted in the-body member or platelike structure 144 in operative association with the port 158. The assembly 160 includes a check valve sum. 4mm.

element 162 having a seal 164 on its end face for abutment with the wall 156 around the periphery of port 158. The check valve element 162 is arranged to seat on the downstream or low pressure side of the wall 156 and preferably is piston shaped so as to provide a skirt 166 into which a calibrated compression spring 168 is fitted. An adjustment screw 170 is threadedly connected to the body member of platelike structure 144, and its position is axially adjustable for varying the effective pressure exerted by the spring 168 on the valve element 166. A nut 172 is threadedly connected to the adjustment screw 170 for securing the latter in its adjusted position. The valve element 166 is adapted to travel in the sleeve 174 which is provided for manufacturing ease in assuring proper alignment and travel of the valve element 166 in the body member or platelike structure 144. Thus, the pressure reducing assembly 160 functions essentially the same as the pressure-reducing assemblies 72 and 102 illustrated and described in FIGS. 7, and 6, respectively.

Similarly to the embodiment of the invention disclosed in FIG. 6, the pressure reducer 54 is provided with an exhaust passageway 176 which permits bypassing the port 158 and its associated pressure-reducing assembly 160. The exhaust passageway 176 is in communication with the opposite ends 148 and 150 of the supply passageway 146, and it includes a check valve element 178 which is retained in position by a keeper spring 180 and which is adapted to unseat and to permit exhaust air to pass around its periphery, but which will check any attempt on the part of the high-pressure air to flow through this exhaust passageway when the directional air valve is set to supply air through the supply passageway 146 via the port 158 and pressure-reducing assembly 160.-

The platelike structure 144 contains two similarly arranged supply and exhaust passageways and also corresponding pressure reducing assemblies 160. The second such set of passageways and assemblies will not be described in detail, since it is identically the same as the one first described. Referring to FIGS. 2 and 3, high-pressure air from the conduit 28 initially flows into manifold 130 via inlet 132 and from the manifold 130 through the port 182 to the directional air valve 52 wherein it will be selectively directed to either one or the other of the inlet ends 148 of the supply passageways 146. Such air, after is pressure has been reduced by operation of the corresponding pressure-reducing assembly 160, will be discharged from the end 150 of the selected passageway. Exhaust air from the cylinder 30 will be returned by the other conduit 56 or 58 for passage through the other exhaust passageway 176 for entry via connections 136 or 138 through the appropriate end 150 and for discharge through the corresponding end 148 to the air valve, where it will be directed to an exhaust port 184 for discharge through the manifold 130.

One of the desirable features of the present invention is the ease with which the pressure reducer can be utilized so that the desired minimum air pressure is available to an air cylinder. Briefly, this setting is established in the following manner, explained in connection with air cylinder 30 and branch 28. Initially, the solenoid directional air valve 52 is energized to direct air to the conduit 56. This pressurized air will seal the element 178, closing exhaust passageway 176 and causing air pressure to build up against the end of valve element 166. When the pressure acting against the end of valve element exceeds the pressure exerted on valve element 166 by the calibrated spring 168, the valve element 166 opens per mitting air to flow to conduit 56 and cylinder 30. Pressure b$ilds in the end of cylinder 30 and conduit 56 until it is equal to the difference between the supply pressure and the effective spring pressure, and when this condition is met, the valve element 166 closes.

If the cylinder piston has not been activated by the existing pressure, the spring pressure is relieved by unscrewing the adjusting screw 170 to reopen the valve element 166 and additional air under pressure is delivered to conduit 56 and air cylinder 30. This action is repeated until piston motion is achieved. When the cylinder piston strokes out, the opposite solenoid of air valve 52 is energized and the above process is repeated until return motion of the piston is achieved.

During these operations, exhaust air unseats the flexible disk element 178 to provide for exhausting of the cylinder 30. Substantially no exhaust back pressure exists because the springs 180 are merely keeper elements which do not materially restrict exhaust flow.

Thus, in operation of the pressure reducer 54, as with respect to the pressure reducers 50 and 32, the air pressure from a regulated main source can be reduced to any selective amount below the pressure of the source, and this can be done without in any way interferring with the operating characteristics of any other branch of the system which for most satisfactory operation relies upon the same or a different air pressure. Thus, the present invention permits relatively large volumes of air to be saved, so as to realize substantial economical benefits. In this respect, there is a substantial benefit derived from the standpoint of compressor wear, operating time, storage tanks and maintenance costs that are required in the production of the high-pressure air. Further, apparatus such as air cylinders can be controlled more easily, because only needed pressures are used. Also, the use of air at the most desirable pressure, results in less wear, and therefore, less maintenance on the cylinder component. The more efficient and better control of the use of the air also has the desirable effect of minimizing pressure drop and pressure surges on the machine header line, adding to the effectiveness of these inventions. It also reduces the shock vibration in the cylinder lines, because as is understood, the amount of shock is directly related to the amount of pressure used. Elimination of excessive pressures has the desirable effect, therefore, of minimizing undesirable shocks during the normal operation of the equipment. Still other advantages are realized, such as reducing exhaust noises and minimizing exhaust contamination of the environment resulting from excessive exhaust fumes being discharged from the cylinders. Still further, the present invention makes it quite simple and very practical to adjust the individual cylinder lines so that any desirable pressure can be utilized in connection with the various air cylinders and with respect to opposite ends of each individual cylinder.

I claim:

1. In a pneumatic system having a source of regulated air at high pressure and apparatus adapted to be operated by air under pressure, a pressure reducer in the system between said source and said apparatus comprising a body member defining a supply passageway having a high-pressure end for receiving air from said source and a low-pressure end for discharging air at a lower pressure to said apparatus, a pressure-adjusting assembly mounted in said body member normally closing said passageway and responsive to a pressure differential of said high-pressure end over said low pressure end to be opened and to remain open in opposition to the high pressure for so long as the pressure differential equals or exceeds a selected magnitude, said assembly including adjustment means extending externally of said body member for selectively varying the extent of opposition exerted by said assembly so as to set the magnitude of the pressure differential at which said assembly will open and thereby to set the pressure of air leaving said pressure reducer, said body member also defining an exhaust passageway which bypasses said assembly and is in communication with the ends of said supply passageway, said exhaust passageway containing a flow control assembly responsive to a pressure greater on said high pressure end than said low pressure end to remain closed and responsive to an applied pressure that is greater on said low pressure end than said high pressure end to open so as to permit exhaust air from said apparatus to flow through said pressure reducer.

2. In a pneumatic system, the pressure reducer that is defined in claim 1, wherein said supply passageway defines a port between its ends and said assembly includes a check valve element normally seated in said passageway to close said port in a direction toward the high-pressure end, an adjustment screw threadedly connected to said body member, and a calibrated spring retained i a state of compression between said check valve element and said adjustment screw for oppo ing pressure exerted against said check valve element from the high-pressure end.

3. In a pneumatic system, the pressure reducer that is defined in claim 2, wherein said body member is a platelike structure adapted to be sandwiched in between a solenoidoperated air valve and a subplate therefor, the ends of said supply passageway being in the upper and lower surfaces of said platelike structure for registry with ends of passageways in said air valve and said subplate.

4. In a pneumatic system, the pressure reducer that is defined in claim 3 wherein said exhaust passageway contains a check element to restrict fiow therethrough from said low pressure end to said high pressure end.

5. In a pneumatic system, the pressure reducer that is' defined in claim 3, wherein said adjustment screw extends out of said platelike structure from one side thereof to facilitate ready access for making desired adjustments.

6. In a pneumatic system, the pressure of that is defined in claim 4, wherein a second symmetrically arranged pressure reducer is formed in said platelike structure and the ends of the supply passageway in the upper and lower surfaces of the platelike structure of the second pressure reducer are also i registry with ends of passageways in said air valve and subplate.

7. in a pneumatic system, the pressure reducer that is defined in claim 1,-wherein said flow control assembly includes means for selectively setting the rate at which exhaust air can flow through said pressure reducer.

8. In a pneumatic system, the pressure reducer that is defined in claim 7, wherein said exhaust passageway defines a port between its ends and said fiow control assembly includes a check valve element normally seated in said exhaust passageway to close said port in a direction toward said low pressure end, and an adjustment screw threadedly connected to said body member for movement toward and away from said check valve element for selectively setting the amount that the valve element can open to permit flow of exhaust air.

9. In a pneumatic system having a source regulated air at high pressure and apparatus adapted to be operated by air under pressure, a pressure reducer in the system between said source and said apparatus comprising a body member defining a supply passageway having high and low pressure ends and a wall separating the ends, said wall having a port providing communication between said highand low-pressure ends, and a pressure adjusting check valve assembly including a check valve element seated on the low-pressure side of said wall normally closing said port, a calibrated spring mounted under compression so as to urge said check valve to its closed position with a load thereon, means in said body member for selectively varying the effective spring pressure exerted by the calibrated spring against the check valve so that air under pressure at a selected relatively lower pressure can be supplied from said source to said apparatus, said body member also defining an exhaust passageway which bypassessaid pressure adjusting check valve assembly and is in communication with the ends of said supply passageway, said exhaust passageway containing a check element responsive to pressure on said high pressure end to remain closed and responsive during exhausting of air from said apparatus to pressure that is greater on said low-pressure end than on said high-pressure end to open.

10. A pressure reducer for use in conjunction with a solenoid-operated air valve which has a subplate with passageways in registry with the passageways extending through the air valve, said pressure reducer comprising a fiat platelike structure defining supply passageways, the ends of which are in the upper and lower surfaces of the structure for registry with passageways in the air valve and subplate, a pressure-adjusting assembly mounted in said body member in association with each sup ly passageway for selectiyely reducing to a desired magnttu e the pressure of air passing therethrough, said flat platelike structure defining a port in each supply passageway, said pressure adjusting assembly including a spring loaded valve element normally closing said port and responsive to air pressure of magnitude greater than the spring load to open said port, said fiat platelike structure also defining an exhaust passageway associated with each supply passageway, each exhaust passageway bypassing the port and pressure-adjusting assembly of its associated supply passageway and being in communication with opposite ends of the supply passageway, and a check element in each exhaust passageway.

11. The pressure reducer that is defined in claim 10, wherein each of said pressure adjusting assemblies includes means for selectively setting from an external location the spring load exerted by the valve element. 

1. In a pneumatic system having a source of regulated air at high pressure and apparatus adapted to be operated by air under pressure, a pressure reducer in the system between said source and said apparatus comprising a body member defining a supply passageway having a high-pressure end for receiving air from said source and a low-pressure end for discharging air at a lower pressure to said apparatus, a pressure-adjusting assembly mounted in said body member normally closing said passageway and responsive to a pressure differential of said high-pressure end over said low pressure end to be opened and to remain open in opposition to the high pressure for so long as the pressure differential equals or exceeds a selected magnitude, said assembly including adjustment means extending externally of said body member for selectively varying the extent of opposition exerted by said assembly so as to set the magnitude of the pressure differential at which said assembly will open and thereby to set the pressure of air leaving said pressure reducer, said body member also defining an exhaust passageway which bypasses said assembly and is in communication with the ends of said supply passageway, said exhaust passageway containing a flow control assembly responsive to a pressure greater on said high pressure end than said low pressure end to remain closed and responsive to an applied pressure that is greater on said low pressure end than said high pressure end to open so as to permit exhaust air from said apparatus to flow through said pressure reducer.
 2. In a pneumatic system, the pressure reducer that is defined in claim 1, wherein said supply passageway defines a port between its ends and said assembly includes a check valve element normally seated in said passageway to close said port in a direction toward the high-pressure end, an adjustment screw threadedly connected to said body member, and a calibrated spring retained i a state of compression between said check valve element and said adjustment screw for opposing pressure exerted against said check valve element from the high-pressure end.
 3. In a pneumatic system, the pressure reducer that is defined in claim 2, wherein said body member is a platelike structure adapted to be sandwiched in between a solenoid-operated air valve and a subplate therefor, the ends of said supply passageway being in the upper and lower surfaces of said platelike structure for registry with ends of passageways in said air valve and said subplate.
 4. In a pneumatic system, the pressure reducer that is defined in claim 3 wherein said exhaust passageway contains a check element to restrict flow therethrough from said low pressure end to said high pressure end.
 5. In a pneumatic system, the pressure reducer that is defined in claim 3, wherein said adjustment screw extends out of said platelike structure from one side thereof to facilitate ready access for making desired adjustments.
 6. In a pneumatic system, the pressure of that is defined in claim 4, wherein a second symmetrically arranged pressure reducer is formed in said platelike structure and the ends of the supply passageway in the upper and lower surfaces of the platelike structure of the second pressure reducer are also i registry with ends of passageways in said air valve and subplate.
 7. In a pneumatic system, the pressure reducer that is defined in claim 1, wherein said flow control assembly includes means for selectively setting the rate at which exhaust aIr can flow through said pressure reducer.
 8. In a pneumatic system, the pressure reducer that is defined in claim 7, wherein said exhaust passageway defines a port between its ends and said flow control assembly includes a check valve element normally seated in said exhaust passageway to close said port in a direction toward said low pressure end, and an adjustment screw threadedly connected to said body member for movement toward and away from said check valve element for selectively setting the amount that the valve element can open to permit flow of exhaust air.
 9. In a pneumatic system having a source o regulated air at high pressure and apparatus adapted to be operated by air under pressure, a pressure reducer in the system between said source and said apparatus comprising a body member defining a supply passageway having high and low pressure ends and a wall separating the ends, said wall having a port providing communication between said high- and low-pressure ends, and a pressure adjusting check valve assembly including a check valve element seated on the low-pressure side of said wall normally closing said port, a calibrated spring mounted under compression so as to urge said check valve to its closed position with a load thereon, means in said body member for selectively varying the effective spring pressure exerted by the calibrated spring against the check valve so that air under pressure at a selected relatively lower pressure can be supplied from said source to said apparatus, said body member also defining an exhaust passageway which bypasses said pressure adjusting check valve assembly and is in communication with the ends of said supply passageway, said exhaust passageway containing a check element responsive to pressure on said high pressure end to remain closed and responsive during exhausting of air from said apparatus to pressure that is greater on said low-pressure end than on said high-pressure end to open.
 10. A pressure reducer for use in conjunction with a solenoid-operated air valve which has a subplate with passageways in registry with the passageways extending through the air valve, said pressure reducer comprising a flat platelike structure defining supply passageways, the ends of which are in the upper and lower surfaces of the structure for registry with passageways in the air valve and subplate, a pressure-adjusting assembly mounted in said body member in association with each supply passageway for selectively reducing to a desired magnitude the pressure of air passing therethrough, said flat platelike structure defining a port in each supply passageway, said pressure adjusting assembly including a spring loaded valve element normally closing said port and responsive to air pressure of magnitude greater than the spring load to open said port, said flat platelike structure also defining an exhaust passageway associated with each supply passageway, each exhaust passageway bypassing the port and pressure-adjusting assembly of its associated supply passageway and being in communication with opposite ends of the supply passageway, and a check element in each exhaust passageway.
 11. The pressure reducer that is defined in claim 10, wherein each of said pressure adjusting assemblies includes means for selectively setting from an external location the spring load exerted by the valve element. 